Along with the gradual progress of the living standard, mobile phones are universally used and become one of the necessaries of life for most people, and communication via mobile phone becomes a major means of communication among people. For example, people grow accustomed to keeping contact with relatives, friends, colleagues, and work fellows, etc. by means of mobile phones.
Under some extreme circumstances, however, like unstable mobile phone signal, low power of mobile phones, or the mobile phone not being carried about, people are unable to communicate normally via their phone, hence experiencing great inconveniences; but prior art does not provide for any good backup means of communication to cope with these circumstances.